Photocurrent Nanoscopy of Quantum Hall Bulk
Understanding nanoscale electronic and thermal transport of two-dimensional (2D) electron systems in the quantum Hall regime, particularly in the bulk insulating state, poses considerable challenges. One of the primary difficulties arises from the presence of chiral edge channels, whose transport be...
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| Main Authors: | , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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American Physical Society
2025-04-01
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| Series: | Physical Review X |
| Online Access: | http://doi.org/10.1103/PhysRevX.15.021026 |
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| author | Ran Jing Boyi Zhou Jiacheng Sun Shoujing Chen Wenjun Zheng Zijian Zhou Heng Wang Lukas Wehmeier Bing Cheng Michael Dapolito Yinan Dong Zengyi Du G. L. Carr Xu Du D. N. Basov Qiang Li Mengkun Liu |
| author_facet | Ran Jing Boyi Zhou Jiacheng Sun Shoujing Chen Wenjun Zheng Zijian Zhou Heng Wang Lukas Wehmeier Bing Cheng Michael Dapolito Yinan Dong Zengyi Du G. L. Carr Xu Du D. N. Basov Qiang Li Mengkun Liu |
| author_sort | Ran Jing |
| collection | DOAJ |
| description | Understanding nanoscale electronic and thermal transport of two-dimensional (2D) electron systems in the quantum Hall regime, particularly in the bulk insulating state, poses considerable challenges. One of the primary difficulties arises from the presence of chiral edge channels, whose transport behavior obscures the investigation of the insulating bulk. Using near-field optical and photocurrent nanoscopy, we probe real-space variations of the optical and thermal dynamics of graphene in the quantum Hall regime without relying on complex sample or electrode geometries. Near the charge-neutrality point, we detect strong optical and photothermal signals from resonant inter-Landau-level (LL) magnetoexciton excitations between the zeroth and ±1 st LLs, which gradually weaken with increasing doping due to Pauli blocking. Interestingly, at higher doping levels and full-integer LL fillings, photothermal signals reappear across the entire sample over an approximately 10-μm scale, indicating unexpectedly long cooling lengths and nonlocal photothermal heating through the insulating bulk. This observation suggests that thermal conductivity persists for the localized states even as electronic transport is suppressed—a clear violation of the Wiedemann-Franz law. Our experiments provide novel insights into nanoscale thermal and electronic transport in incompressible 2D gases, highlighting the roles of magnetoexcitons and chiral edge states in the thermo-optoelectric dynamics of the Dirac quantum Hall state. |
| format | Article |
| id | doaj-art-d939d2a8581b4ce4a3232c8c36d7774f |
| institution | OA Journals |
| issn | 2160-3308 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | American Physical Society |
| record_format | Article |
| series | Physical Review X |
| spelling | doaj-art-d939d2a8581b4ce4a3232c8c36d7774f2025-08-20T02:12:10ZengAmerican Physical SocietyPhysical Review X2160-33082025-04-0115202102610.1103/PhysRevX.15.021026Photocurrent Nanoscopy of Quantum Hall BulkRan JingBoyi ZhouJiacheng SunShoujing ChenWenjun ZhengZijian ZhouHeng WangLukas WehmeierBing ChengMichael DapolitoYinan DongZengyi DuG. L. CarrXu DuD. N. BasovQiang LiMengkun LiuUnderstanding nanoscale electronic and thermal transport of two-dimensional (2D) electron systems in the quantum Hall regime, particularly in the bulk insulating state, poses considerable challenges. One of the primary difficulties arises from the presence of chiral edge channels, whose transport behavior obscures the investigation of the insulating bulk. Using near-field optical and photocurrent nanoscopy, we probe real-space variations of the optical and thermal dynamics of graphene in the quantum Hall regime without relying on complex sample or electrode geometries. Near the charge-neutrality point, we detect strong optical and photothermal signals from resonant inter-Landau-level (LL) magnetoexciton excitations between the zeroth and ±1 st LLs, which gradually weaken with increasing doping due to Pauli blocking. Interestingly, at higher doping levels and full-integer LL fillings, photothermal signals reappear across the entire sample over an approximately 10-μm scale, indicating unexpectedly long cooling lengths and nonlocal photothermal heating through the insulating bulk. This observation suggests that thermal conductivity persists for the localized states even as electronic transport is suppressed—a clear violation of the Wiedemann-Franz law. Our experiments provide novel insights into nanoscale thermal and electronic transport in incompressible 2D gases, highlighting the roles of magnetoexcitons and chiral edge states in the thermo-optoelectric dynamics of the Dirac quantum Hall state.http://doi.org/10.1103/PhysRevX.15.021026 |
| spellingShingle | Ran Jing Boyi Zhou Jiacheng Sun Shoujing Chen Wenjun Zheng Zijian Zhou Heng Wang Lukas Wehmeier Bing Cheng Michael Dapolito Yinan Dong Zengyi Du G. L. Carr Xu Du D. N. Basov Qiang Li Mengkun Liu Photocurrent Nanoscopy of Quantum Hall Bulk Physical Review X |
| title | Photocurrent Nanoscopy of Quantum Hall Bulk |
| title_full | Photocurrent Nanoscopy of Quantum Hall Bulk |
| title_fullStr | Photocurrent Nanoscopy of Quantum Hall Bulk |
| title_full_unstemmed | Photocurrent Nanoscopy of Quantum Hall Bulk |
| title_short | Photocurrent Nanoscopy of Quantum Hall Bulk |
| title_sort | photocurrent nanoscopy of quantum hall bulk |
| url | http://doi.org/10.1103/PhysRevX.15.021026 |
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